At present, touch devices (for example, touch mobile phones) generally detect pressure caused by touches of users' hands by using a pressure sensor. The pressure detection structure of a touch device is mounted on a middle frame of the touch device, and includes a cover, a display device and a pressure sensor. When the display device is an LCD display device (that is, a display screen), the display module is a liquid crystal module. The display device further includes optical members and a housing bearing the liquid crystal module and the optical members. When the display device is an LED display device, the display module is an LED module, and the display device further includes a flexible foam layer for use in light shading and cushioning.
As illustrated in FIG. 1.1, when the display device is an LCD display device (that is, a display screen), the pressure detection structure of the touch device includes a cover 1, a middle frame 4, a display screen 2 and a pressure sensor 3. The pressure sensor 3, the display screen 2 and the cover 1 are sequentially stacked in the middle frame from bottom to top, and a gap 5 is present between the pressure sensor 3 and the display screen 2. Generally, the pressure sensor 3 is a capacitive sensor, and as illustrated in FIG. 1.2, includes a substrate 6 and detection electrodes 7 arranged in a matrix form on the substrate 6. The detection electrodes 7 of the pressure sensor 3 and an external reference electrode form the capacitance as illustrated in FIG. 1.3. Each of the detection electrodes 7 on the substrate 6 forms a capacitance C with a reference electrode 9. In the pressure detection structure as illustrated in FIG. 1.1, the reference electrode is an electrically conductive layer in the display screen, the capacitance structure thereof is as illustrated in FIG. 1.4. Pressure detection is practiced as follows: when a force is applied to the cover 1, the cover 1 deforms, such that the spacing between the pressure sensor 3 and the display screen 2 is changed, and thus the capacitance between the pressure sensor 3 and an electrically conductive layer of the display screen 2 is changed. Accordingly, the pressure is identified according to the variation quantity of the capacitance.
As seen from the implementation principle, a detection spacing between the display screen 2 and the pressure sensor 3 needs to be well controlled, wherein the detection spacing is the gap 5 as illustrated in FIG. 1.1. However, the gap 5 is subject to complicated and more working processes and masses of parts to be assembled during the mass production, and thus the assembling is subject to a great tolerance. In addition, the tolerance of the spacing between the display screen 2 and the pressure sensor 3 of different machines may affect consistency of the machines, and thus the user experience is different between the different machines. Moreover, falloff and extrusion-caused deformation of the entire product may simply change the gap, thereby lowering reliability of the products.
Therefore, it is a technical problem to be solved urgently in the related art on how to perform pressure detection.